Process of glutamic acid recovery from solutions



solution of hydrochloric acid under certain contrated hydrochloric acid. Merely as an illusditlons and from the resulting glutamic acid hytrativeexample of a process of this latter type drochloride solution \a considerable proportion the following sequence of operations may be emof the glutamic acid may be separated by varployed. ious methods, one suitable method being the One thousand parts of crude glutamic acid addition, to the glutamic acid hydrochloride sohydrochloride containing some ammonium chlolution, of an alkali, such for example as sodium ride (such as may result from hydrolyzing pro-- hydroxide, in such proportion as to combine with tein matter with hydrochloric acid) is dissolved the hydrochloric acid forming a constituent part in three thousand parts of water, the solution of the glutamic acid hydrochloride (and also is treated with any suitable decolorizing carbon with any free hydrochloric acid present). By or the like, analyzed to determine the amounts 15 such treatment, a large proportion of the gluof ammonium chloride and total hydrochloric tamic acid present is precipitated in the form acid present and to calculate the amount of of free glutamic acid and by suitable repeated hydrochloric acid to be neutralized, and the concentrations of the remaining solution, folamount of ammonium formate or acetate or lowed by cooling, further quantities of free glucalcium formate or acetate required for reactamic acid may be crystallized. However, in tion with all free hydrochloric acid and that processes of such general character, even after Combined h the glutamic acid in rde tfl prerepeated crystallizations, a mother liquor cuscip e m c a d is calculated and such tomarily remains as a final product containing calculated quantity of ammonium formate or about 10% to 20% of the total amount of gluacetate or calcium formate or acetate is added 25 tamic acid present in the original reaction prodto the solution (a quantity of 256 parts of crysuct or hydrolysate and it has heretofore been tallized ammonium formate having in one inconsidered impractical to recover this residual stance been found proper for this purpose). content of glutamic acid from the final mother Substantially 80% to 90% of the glutamic acid liquor. contained in the liquor thus treated is separated An object of my present invention is the subin crystalline form immediately upon, the addistantially complete recovery of the contained tion of the ammonium formate or other reagent glutamic acid from mother liquors, such as those added and may be isolated from the associated of the character just mentioned, in an economiliquid by filtration. The remaining mother liqcal and. p ractical manner so that substantially uor still contains a considerable proportion of all of the glutamic acid formed in a process such the glutamic acid, which has failed to separate as mentioned is eventually recovered. in the crystallization just mentioned, together If a mother liquor is to betreated which is withsubstantial proportions of ammonium chloderived from a process in which ammonium salts ride and formic or acetic acid. To this mother such as ammonium acetate or ammonium forliquor there is added a quantity of calcium hymate or nitrogen bases such as pyridine have droxide slightly in excess over the calculated been used for precipitating the glutamic acid, amount proportioned to provide sufficient calor if a solution is to be treated such as is decium hydroxide for reaction with the ammonium rived from crude glutamic acid hydrochloride chloride present and with any other ammonium containing ammonium chloride, the treatment salts present and the ammonia liberated is disl of the final mother liquor involves first making tilled from the solution, preferably under a rer it alkaline with the hydroxide of an alkaline duced pressure, until the solution is ,sirbstantialearth metal such as the hydroxide of barium, cal- 1y freed from ammonia. Th'' distilled ammonia f cium or strontium; ammonia or nitrogen bases may be recovered in any suitable manner and such as pyridine which may be present are then at the end of the ammonia distillation the reremoved from the solution by distillation and maining mixture is treated with sufflcient sulare recovered; and thereafter the alkaline earth furic acid (suitably in the form of a dilute aque metal is removed from the solution by precipious solution of sulfuric acid) to combine with tating it (suitably by adding a combining prothe calcium present and calciumsulfate thus portion of sulfuric acid or oxalic acid). After precipitated is separated from the liquid by 56 Patented Jim. 9, 1940 PROCESS OF GLUTAMIC ACID RECOVERY FROM SOLUTIONS N. Y., assignor to Stand- New York, N. Y., a

Gza Braun, New York,

ard Brands Incorporated, corporation of Delaware No Drawing Application October 15, 1936, Serial No. 105,829

this precipitation, the precipitate is separated, as by filtration, and the glutamic acid hydrochloride remaining in thesolution is recovered, after I concentrating the solution, by adding concen- 5 Claims.

In the production and recovery of glutamic acid, the latter may be formed by the treatment of a glutamic acid-yielding material such as wheat gluten with an acid such as an aqueous acetate or calcium formate or acetate which.

may be used for reaction with additional material repeatedly.

The residual syrupy material or semi-crystalline mass is treated with /2 to 1 times its volume concentrated (32%) hydrochloric acid (about 250 parts of hydrochloric acid of 32% strength having been found a proper proportion for this purpose in working with quantities of materials as heretofore stated in the illustrative example), the treated material is cooled preferably to about C. and is maintained at about this temperature for about an hour with occasional stirring. By this treatment, glutamic acid hydrochloride is deposited as a crystalline precipitate. This precipitate is separated by filtration and the glutamic acid hydrochloride crystals thus separated are washed with a small quantity of ice cold concentrated hydrochloric acid and dried. About 100 parts of pure glutamic acid hydrochloride is thus obtained, additional to about 800-900 parts previously recovered in the process.

As hereinbefore mentioned, an alkali metal hydroxide can also be applied in the precipitation of the main portion of glutamic acid. However, the use of such hydroxides or of any other basic substance, which cannot subsequently be removed economically from the mother liquor, is not advisable since then the chlorides formed from bases will either contaminate the glutamic acid hydrochloride, if they are insoluble in concentrated hydrochloric acid (such as NaCl or or KCl, etc.) or if soluble in it they may increase the solubility of glutamic acid hydrochloride to such an extent that its crystallization may be entirely prevented. Nevertheless, the above process may still be successfully applied even in such cases since the removal of ammonium chloridederived from the crude glutamic acid hydrochloride-improves the mother liquor and some of the glutamic acid will be crystallizable in the form of its hydrochloride.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a process of recovery of glutamic acid from a solution containing the same, the step which comprises precipitating glutamic acid from the solution by the addition of ammonium formate.

2. In a process of recovery of glutamic acid from a solution, the step which comprises precipitating glutamic acid from the solution by the addition of ammonium acetate.

3. In a process of recovery of glutamic acid from a solution containing the same, the steps which comprise precipitating glutamic acid from the solution by the addition of an ammonium salt of an innocuous distillable organic acid, separating the precipitated glutamic acid and subsequently adding, to the mother liquor remaining after precipitated glutamic acid has been separated from the so-treated solution, a reagent which will liberate the free organic acid from the added ammonium salt, and distilling and recovering the liberated organic acid.

4. In a process as defined in claim 1, the steps of removing precipitated glutamic acid from the solution and thereafter successively adding, to the remaining mother liquor, reagents respectively liberating ammonia and formic acid and successively distilling and recovering the liberated ammonia and the liberated formic acid.

5. In a process as defined in claim 1, the steps which comprise removing glutamic acid from the solution after its precipitation, adding a reagent liberating ammonia to the remaining mother liquor, distilling the liberated ammonia, recovering the distilled ammonia, reacting the distilled ammonia with formic acid and recovering the ammonium formate produced by this reaction, and adding ammonium formate so produced to a glutamic acid-containing solution under such conditions as to effect precipitation of the glutamic acid thereby from said solutions.

GEZA BRAUN. 

